--- st.c
+++ st.c
@@ -1224,92 +1361,118 @@ kscrollup(const Arg* a)
 {
 	int n = a->i;
 
+	if (!term.histf || IS_SET(MODE_ALTSCREEN))
+		return;
+
 	if (n < 0)
-		n = term.row + n;
+		n = MAX(term.row / -n, 1);
 
-	if (term.scr <= HISTSIZE-n) {
+	if (term.scr + n <= term.histf) {
 		term.scr += n;
-		selscroll(0, n);
-		tfulldirt();
+	} else {
+		n = term.histf - term.scr;
+		term.scr = term.histf;
 	}
+
+	if (sel.ob.x != -1 && !sel.alt)
+		selmove(n); /* negate change in term.scr */
+	tfulldirt();
 }
 
 void
-tscrolldown(int orig, int n, int copyhist)
+tscrolldown(int top, int n)
 {
-	int i;
+	int i, bot = term.bot;
 	Line temp;
 
-	LIMIT(n, 0, term.bot-orig+1);
-	if (copyhist) {
-		term.histi = (term.histi - 1 + HISTSIZE) % HISTSIZE;
-		temp = term.hist[term.histi];
-		term.hist[term.histi] = term.line[term.bot];
-		term.line[term.bot] = temp;
-	}
-
+	if (n <= 0)
+		return;
+	n = MIN(n, bot-top+1);
 
-	tsetdirt(orig, term.bot-n);
-	tclearregion(0, term.bot-n+1, term.col-1, term.bot);
+	tsetdirt(top, bot-n);
+	tclearregion(0, bot-n+1, term.col-1, bot, 1);
 
-	for (i = term.bot; i >= orig+n; i--) {
+	for (i = bot; i >= top+n; i--) {
 		temp = term.line[i];
 		term.line[i] = term.line[i-n];
 		term.line[i-n] = temp;
 	}
 
-	if (term.scr == 0)
-		selscroll(orig, n);
+	if (sel.ob.x != -1 && sel.alt == IS_SET(MODE_ALTSCREEN))
+		selscroll(top, bot, n);
 }
 
 void
-tscrollup(int orig, int n, int copyhist)
+tscrollup(int top, int bot, int n, int mode)
 {
-	int i;
+	int i, j, s;
+	int alt = IS_SET(MODE_ALTSCREEN);
+	int savehist = !alt && top == 0 && mode != SCROLL_NOSAVEHIST;
 	Line temp;
 
-	LIMIT(n, 0, term.bot-orig+1);
-
-	if (copyhist) {
-		term.histi = (term.histi + 1) % HISTSIZE;
-		temp = term.hist[term.histi];
-		term.hist[term.histi] = term.line[orig];
-		term.line[orig] = temp;
+	if (n <= 0)
+		return;
+	n = MIN(n, bot-top+1);
+
+	if (savehist) {
+		for (i = 0; i < n; i++) {
+			term.histi = (term.histi + 1) % HISTSIZE;
+			temp = term.hist[term.histi];
+			for (j = 0; j < term.col; j++)
+				tclearglyph(&temp[j], 1);
+			term.hist[term.histi] = term.line[i];
+			term.line[i] = temp;
+		}
+		term.histf = MIN(term.histf + n, HISTSIZE);
+		s = n;
+		if (term.scr) {
+			j = term.scr;
+			term.scr = MIN(j + n, HISTSIZE);
+			s = j + n - term.scr;
+		}
+		if (mode != SCROLL_RESIZE)
+			tfulldirt();
+	} else {
+		tclearregion(0, top, term.col-1, top+n-1, 1);
+		tsetdirt(top+n, bot);
 	}
 
-	if (term.scr > 0 && term.scr < HISTSIZE)
-		term.scr = MIN(term.scr + n, HISTSIZE-1);
-
-	tclearregion(0, orig, term.col-1, orig+n-1);
-	tsetdirt(orig+n, term.bot);
-
-	for (i = orig; i <= term.bot-n; i++) {
+	for (i = top; i <= bot-n; i++) {
 		temp = term.line[i];
 		term.line[i] = term.line[i+n];
 		term.line[i+n] = temp;
 	}
 
-	if (term.scr == 0)
-		selscroll(orig, -n);
+	if (sel.ob.x != -1 && sel.alt == alt) {
+		if (!savehist) {
+			selscroll(top, bot, -n);
+		} else if (s > 0) {
+			selmove(-s);
+			if (-term.scr + sel.nb.y < -term.histf)
+				selremove();
+		}
+	}
 }
 
 void
-selscroll(int orig, int n)
+selmove(int n)
 {
-	if (sel.ob.x == -1)
-		return;
+	sel.ob.y += n, sel.nb.y += n;
+	sel.oe.y += n, sel.ne.y += n;
+}
+
+void
+selscroll(int top, int bot, int n)
+{
+	/* turn absolute coordinates into relative */
+	top += term.scr, bot += term.scr;
 
-	if (BETWEEN(sel.nb.y, orig, term.bot) != BETWEEN(sel.ne.y, orig, term.bot)) {
+	if (BETWEEN(sel.nb.y, top, bot) != BETWEEN(sel.ne.y, top, bot)) {
 		selclear();
-	} else if (BETWEEN(sel.nb.y, orig, term.bot)) {
-		sel.ob.y += n;
-		sel.oe.y += n;
-		if (sel.ob.y < term.top || sel.ob.y > term.bot ||
-		    sel.oe.y < term.top || sel.oe.y > term.bot) {
+	} else if (BETWEEN(sel.nb.y, top, bot)) {
+		selmove(n);
+		if (sel.nb.y < top || sel.ne.y > bot)
 			selclear();
-		} else {
-			selnormalize();
-		}
 	}
 }
 
@@ -1922,24 +2092,24 @@ csihandle(void)
 	case 'K': /* EL -- Clear line */
 		switch (csiescseq.arg[0]) {
 		case 0: /* right */
-			tclearregion(term.c.x, term.c.y, term.col-1,
-					term.c.y);
+			tclearregion(term.c.x, term.c.y, term.col-1, term.c.y, 1);
 			break;
 		case 1: /* left */
-			tclearregion(0, term.c.y, term.c.x, term.c.y);
+			tclearregion(0, term.c.y, term.c.x, term.c.y, 1);
 			break;
 		case 2: /* all */
-			tclearregion(0, term.c.y, term.col-1, term.c.y);
+			tclearregion(0, term.c.y, term.col-1, term.c.y, 1);
 			break;
 		}
 		break;
 	case 'S': /* SU -- Scroll <n> line up */
 		DEFAULT(csiescseq.arg[0], 1);
-		tscrollup(term.top, csiescseq.arg[0], 0);
+		/* xterm, urxvt, alacritty save this in history */
+		tscrollup(term.top, term.bot, csiescseq.arg[0], SCROLL_SAVEHIST);
 		break;
 	case 'T': /* SD -- Scroll <n> line down */
 		DEFAULT(csiescseq.arg[0], 1);
-		tscrolldown(term.top, csiescseq.arg[0], 0);
+		tscrolldown(term.top, csiescseq.arg[0]);
 		break;
 	case 'L': /* IL -- Insert <n> blank lines */
 		DEFAULT(csiescseq.arg[0], 1);
@@ -1979,9 +2151,9 @@ csihandle(void)
 		break;
 	case 'n': /* DSR – Device Status Report (cursor position) */
 		if (csiescseq.arg[0] == 6) {
-			len = snprintf(buf, sizeof(buf), "\033[%i;%iR",
+			n = snprintf(buf, sizeof(buf), "\033[%i;%iR",
 					term.c.y+1, term.c.x+1);
-			ttywrite(buf, len, 0);
+			ttywrite(buf, n, 0);
 		}
 		break;
 	case 'r': /* DECSTBM -- Set Scrolling Region */